1. Field of the Invention
The present invention relates to a system and method for fitting a new design with existing conditions.
2. Related Art
CAD software is well-known, and used by architects, engineers, designers, planners, and the like to create precision models and technical illustrations. It is used to create two-dimensional (2-D) drawings, maps, and three-dimensional (3-D) models. CAD software may be used to design roadways, highways and the like. Applications such as MicroStation® products, which are developed by Bentley Systems, Inc., Exton, Pa. U.S.A., and AutoCAD® products, which are developed by Autodesk, Inc., San Rafael, Calif., U.S.A., are typical of such CAD software, which may be used in the engineering, construction, and operations (ECO) marketplace.
CAD software, such as InRoads®, one of the MicroStation® products from Bentley Systems, provides a graphic environment to create a three-dimension digital surface such as a roadway. InRoads® provides functionality that allows a user to define roadway conditions, generate cross-sections and three-dimensional models, calculate volumes, generate reports, evaluate the design, and create plan and profile sheets. These extensive features, along with additional application add-in tools, make designing a complex highway system or simply laying out a small subdivision an interactive and easy process.
Typically the surface of a road is defined using cross sections, or templates. A template defines the cross section of a road at a single point. However, templates define an entire roadway surface when they are applied successively along an alignment. Placing one or more templates repeatedly along a path defined by horizontal and vertical alignments generates a three-dimensional corridor model. The distance between each application of the template is determined by an interval parameter. The smaller the interval, the more accurate the model.
Part of the design process is to fit the new design into existing conditions. This may be done using end conditions. End conditions define the connection of a point in the design to a target. In roadway design, end conditions usually connect the new roadway design with the existing ground, for example, via a side slope extending from the roadway surface. The end conditions may be line segments that are projected transverse from an edge of a typical section, and seek an intersection with a target, usually the existing ground. The segments are combined in sequences which are considered to be successful if they hit the target. Multiple design scenarios may be checked at each location at which a typical section is placed along a design. A designer does not need to manually create the design at each point.
FIG. 1 illustrates an example of end conditions in roadway design. The edge of the roadway is defined as point H. Depending on the location of the existing ground at this location, it may be desired to have a side slope extend from the edge of the roadway with a negative slope to point A or a positive slope to point B. End conditions can be used to define the applicable design. A decision table, shown below, may be used to define the end conditions. Decision tables follow along a linear path (such as the edge of the road or a graphic element) and define transverse geometry at predefined intervals along that path. The transverse geometry is defined using line segments that extend perpendicular from a linear control. The line segments are connected end-to-end to represent a cross section of the design.
A decision table is a sequential list of segments. A record contains names for the start point and the end point, a slope, and a width that defines each segment. The purpose of listing segments is that one of them should produce an intersection (usually with the existing ground). If a segment does not produce an intersection, the table moves on to the next segment. When a segment does produce a final intersection, the table stops.
The example shown in FIG. 1 presents a very simple decision table. The decision table defines just two segments: one for cut side slopes and one for fill slopes. The following list represents the decision table:
StartEndSlopeWidthHA−0.351,000 mHB0.351,000 mThis decision table contains two records. Each record defines a segment. Referring to FIG. 1, the first record defines segment HA, which extends from the point H for 1,000 meters of width, sloping downward at 35% grade. If this slope does not intersect the ground, the next segment in the table is attempted. The second segment HB also extends from point H for 1,000 meters, but is sloping up at 35% grade.
Decision tables and other text-based tools have a disadvantage of being difficult to visualize. This is particularly true when a designer is dealing with a complex series of tables. This results in the designer having to go deep into the design process just to test the validity of the decision tables or other text-based tool being used. Thus, there is a need for a simple process for handling end conditions.